Di Zhe didn't know what she was thinking and thought about how she was willing to teach him this method, so he was even touched.
However, after learning the method and interrogating each and every single one, he finally realised that she wasn't really that kind hearted after all. She merely taught him this so she wouldn't have to do this herself.
As such, he came to look for Di Yi and Di Er as well, teaching them how to do it. He got them to interrogate those people and to take the information from their minds.
Di Yi and Di Er learnt how to do it and it made the subsequent interrogations a lot more effective. They also managed to obtain quite a bit of information.
After Sima You Yue imparted the method to Di Zhe, she immediately handed him the task of interrogation.
"Just give me the tasks involving the Enchanted Music Sect." Di Zhe said, "It would be better if you interacted less with those from the Soul Sect right now, got it?"